Japan’s nuclear crisis intensified yesterday as authorities raced to combat the threat of multiple reactor meltdowns and more than 170,000 people evacuated the quake and tsunami-savaged northeastern coast where fears spread over possible radioactive contamination.

Nuclear plant operators were frantically trying to keep temperatures down in a series of nuclear reactors — including one where officials feared a partial meltdown could be happening yesterday — to prevent the situation from deteriorating.

Japanese Chief Cabinet Secretary Yukio Edano said yesterday that a hydrogen explosion could occur at Unit 3 of the Fukushima Dai-ichi nuclear complex, the latest reactor to face a possible meltdown.